Correct or improve the translation of the following Chinese sent

Correct or improve the translation of the following Chinese sentences.原文:理论上看起来容易的事情做起来却往往非常困难。 译文:That seems easy in theory is often immensely difficult to achieve.改译:
【正确答案】:

WHAT SEEMS EASY IN THEORY IS OFTEN IMMENSELY DIFFICULT TO ACHIEVE.


【题目解析】:“理论上看起来容易的事情”在句中作主语,又是从句,并在从句中作主语,因此引导主语从句应用引导词what。